This application relates to belt attachments, specifically to an improved system for belt attachments that sustain large loads and very high cycle fatigue. Typical applications include conveyors, bucket excavators, elevators, vertical lifts, and similar machines used to transfer a load from one location to another. Belt attachment systems may also be used in power conversion machines, such as in hydropower or wind power devices, where it is desired that large loads are passed from an attached body to a belt that then drives a generator. However, currently available belt attachment systems lack the ability to withstand large loads and high cycle fatigue.
Chains have been used in place of belts for some systems, but chains tend to be heavy, consist of many moving parts, and suffer from high wear rates and high maintenance cost. Due to these issues, chain-based systems often demand frequent maintenance. Chain, systems also require complex systems to maintain chain tension as the system wears.
Belt systems have advantages over chain systems including relative simplicity, lower maintenance requirements, and reduced noise. Belt attachments can be used on a single belt, with attached bodies as is typical of conveyor systems. In this case, loads tend to be light relative to the size and power rating of the belt and loads are typically transferred along the flat portion of the belt. Belt attachments can also be used to support attached bodies between a plurality of belts such as in vertical lifts. In this case and with heavier loads, rigid attachments to the belt can suffer from bending moment induced stresses resulting in relatively low fatigue lifetimes.
Current methods used to secure a single attachment to a belt are generally unsatisfactory for the transfer of large loads and high fatigue lifetimes. Some common securing methods include fastening (bolts or rivets), gluing, and vulcanizing. Bolts or rivets that, by themselves, secure attachments suffer from low belt fatigue lifetimes by gradually elongating the through holes in the belt. Gluing is a messy process and does not allow the attachment to be removed from the belt. Furthermore, glue degrades and breaks down relatively quickly in operation due to peeling forces as the belt bends around the sprocket. Vulcanizing elastomeric members to a belt requires special tooling and the resulting attachments do not support large loads.
Other methods of belt attachment have been used to address the issue of supporting the attachment as it goes around the sprocket. This is a problem area for many attachment methods because the flat contact area changes to a line contact around the sprocket and is therefore not capable of supporting a pitching moment. Also, the straight-line distance between two adjacent belt teeth changes around the sprocket, which makes multiple attachment points difficult. Existing solutions either support relatively low loads or suffer from high wear rates.
Different belt attachment systems and different applications require different boundary conditions for connecting an implement to the belt attachment(s). A single belt attachment may need to allow, restrain, or fix six degrees of freedom.